Background. The benefits of establishing early coronary reperfusion in acute myocardial infarction (MI) have now been unequivocally established. However, current pharmacological strategies fail to achieve effective reperfusion in 30% or more of patients, and many patients with occluded infarct arteries do not meet current criteria for use of these agents. Early angioplasty, an effective reperfusion method, is available to a small proportion of potentially eligible US acute MI patients. Hence, a substantial number of acute MI patients pass the time when reperfusion therapy has any documented benefit (12-24 hours) with a persistently closed infarct vessel. Several lines of experimental and clinical evidence suggest that late reperfusion of these patients could provide clinically significant reductions in mortality and morbidity. Hypothesis: The central hypothesis of the Open Artery Trial is that opening an occluded infarct artery 3-21 days after an acute MI in high-risk asymptomatic patients (ejection fraction less than 50% or proximal occlusion of a large coronary artery) will reduce the composite endpoint of mortality, recurrent MI, and hospitalization for NYHA class IV congestive hear failure (CHF) over an average three year follow-up. Specific aims. The study will be a prospective clinical trial with 3,200 patients randomly allocated in equal proportions to two tretments arms over two years. One treatment will consist of conventional medical management (including aspirin, beta blockers, ACE inhibitors, and risk factor modification). The experimental treatment will consist of conventional medical therapy plus percutaneous coronary intervention and coronary stenting. Clinical outcomes will be compared using an intention-to-treat analysis. We have one primary specific aim: 1) To compare the composite outcome of all-cause mortality, non-fetal MI and hospitalization of NYHA class IV CHF based on an average three year follow-up among patients assigned to the two treatments. We have three secondary specific aims: 1) To compare the individual components of the study composite primary endpoint in the two treatment arms. 2) To compare the medical costs of the two treatments and assess the cost effectiveness of percutaneous revascularization in the study population. 3) To compare health-related quality of life in the two treatment groups. Operations. The Luke's-Roosevelt Hospital in New York City. The Data Coordinating Center (DCC) is at the Maryland Medical Research Institute. The Economics and Quality of Life Coordinating Center is at Duke University. The Angiographic Core Laboratory is at the University of British Columbia.